1 /* 2 * Copyright (c) Christos Zoulas 2003. 3 * All Rights Reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice immediately at the beginning of the file, without modification, 10 * this list of conditions, and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR 19 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 */ 27 28 #ifdef WIN32 29 #include <windows.h> 30 #include <shlwapi.h> 31 #endif 32 33 #include "file.h" 34 35 #ifndef lint 36 FILE_RCSID("@(#)$File: magic.c,v 1.117 2021/12/06 15:33:00 christos Exp $") 37 #endif /* lint */ 38 39 #include "magic.h" 40 41 #include <stdlib.h> 42 #include <unistd.h> 43 #include <string.h> 44 #ifdef QUICK 45 #include <sys/mman.h> 46 #endif 47 #include <limits.h> /* for PIPE_BUF */ 48 49 #if defined(HAVE_UTIMES) 50 # include <sys/time.h> 51 #elif defined(HAVE_UTIME) 52 # if defined(HAVE_SYS_UTIME_H) 53 # include <sys/utime.h> 54 # elif defined(HAVE_UTIME_H) 55 # include <utime.h> 56 # endif 57 #endif 58 59 #ifdef HAVE_UNISTD_H 60 #include <unistd.h> /* for read() */ 61 #endif 62 63 #ifndef PIPE_BUF 64 /* Get the PIPE_BUF from pathconf */ 65 #ifdef _PC_PIPE_BUF 66 #define PIPE_BUF pathconf(".", _PC_PIPE_BUF) 67 #else 68 #define PIPE_BUF 512 69 #endif 70 #endif 71 72 private void close_and_restore(const struct magic_set *, const char *, int, 73 const struct stat *); 74 private int unreadable_info(struct magic_set *, mode_t, const char *); 75 private const char* get_default_magic(void); 76 #ifndef COMPILE_ONLY 77 private const char *file_or_fd(struct magic_set *, const char *, int); 78 #endif 79 80 #ifndef STDIN_FILENO 81 #define STDIN_FILENO 0 82 #endif 83 84 #ifdef WIN32 85 /* HINSTANCE of this shared library. Needed for get_default_magic() */ 86 static HINSTANCE _w32_dll_instance = NULL; 87 88 static void 89 _w32_append_path(char **hmagicpath, const char *fmt, ...) 90 { 91 char *tmppath; 92 char *newpath; 93 va_list ap; 94 95 va_start(ap, fmt); 96 if (vasprintf(&tmppath, fmt, ap) < 0) { 97 va_end(ap); 98 return; 99 } 100 va_end(ap); 101 102 if (access(tmppath, R_OK) == -1) 103 goto out; 104 105 if (*hmagicpath == NULL) { 106 *hmagicpath = tmppath; 107 return; 108 } 109 110 if (asprintf(&newpath, "%s%c%s", *hmagicpath, PATHSEP, tmppath) < 0) 111 goto out; 112 113 free(*hmagicpath); 114 free(tmppath); 115 *hmagicpath = newpath; 116 return; 117 out: 118 free(tmppath); 119 } 120 121 static void 122 _w32_get_magic_relative_to(char **hmagicpath, HINSTANCE module) 123 { 124 static const char *trypaths[] = { 125 "%s/share/misc/magic.mgc", 126 "%s/magic.mgc", 127 }; 128 LPSTR dllpath; 129 size_t sp; 130 131 dllpath = calloc(MAX_PATH + 1, sizeof(*dllpath)); 132 133 if (!GetModuleFileNameA(module, dllpath, MAX_PATH)) 134 goto out; 135 136 PathRemoveFileSpecA(dllpath); 137 138 if (module) { 139 char exepath[MAX_PATH]; 140 GetModuleFileNameA(NULL, exepath, MAX_PATH); 141 PathRemoveFileSpecA(exepath); 142 if (stricmp(exepath, dllpath) == 0) 143 goto out; 144 } 145 146 sp = strlen(dllpath); 147 if (sp > 3 && stricmp(&dllpath[sp - 3], "bin") == 0) { 148 _w32_append_path(hmagicpath, 149 "%s/../share/misc/magic.mgc", dllpath); 150 goto out; 151 } 152 153 for (sp = 0; sp < __arraycount(trypaths); sp++) 154 _w32_append_path(hmagicpath, trypaths[sp], dllpath); 155 out: 156 free(dllpath); 157 } 158 159 #ifndef BUILD_AS_WINDOWS_STATIC_LIBARAY 160 /* Placate GCC by offering a sacrificial previous prototype */ 161 BOOL WINAPI DllMain(HINSTANCE, DWORD, LPVOID); 162 163 BOOL WINAPI 164 DllMain(HINSTANCE hinstDLL, DWORD fdwReason, 165 LPVOID lpvReserved __attribute__((__unused__))) 166 { 167 if (fdwReason == DLL_PROCESS_ATTACH) 168 _w32_dll_instance = hinstDLL; 169 return 1; 170 } 171 #endif 172 #endif 173 174 private const char * 175 get_default_magic(void) 176 { 177 static const char hmagic[] = "/.magic/magic.mgc"; 178 static char *default_magic; 179 char *home, *hmagicpath; 180 181 #ifndef WIN32 182 struct stat st; 183 184 if (default_magic) { 185 free(default_magic); 186 default_magic = NULL; 187 } 188 if ((home = getenv("HOME")) == NULL) 189 return MAGIC; 190 191 if (asprintf(&hmagicpath, "%s/.magic.mgc", home) < 0) 192 return MAGIC; 193 if (stat(hmagicpath, &st) == -1) { 194 free(hmagicpath); 195 if (asprintf(&hmagicpath, "%s/.magic", home) < 0) 196 return MAGIC; 197 if (stat(hmagicpath, &st) == -1) 198 goto out; 199 if (S_ISDIR(st.st_mode)) { 200 free(hmagicpath); 201 if (asprintf(&hmagicpath, "%s/%s", home, hmagic) < 0) 202 return MAGIC; 203 if (access(hmagicpath, R_OK) == -1) 204 goto out; 205 } 206 } 207 208 if (asprintf(&default_magic, "%s:%s", hmagicpath, MAGIC) < 0) 209 goto out; 210 free(hmagicpath); 211 return default_magic; 212 out: 213 default_magic = NULL; 214 free(hmagicpath); 215 return MAGIC; 216 #else 217 hmagicpath = NULL; 218 219 if (default_magic) { 220 free(default_magic); 221 default_magic = NULL; 222 } 223 224 /* Before anything else, try to get a magic file from user HOME */ 225 if ((home = getenv("HOME")) != NULL) 226 _w32_append_path(&hmagicpath, "%s%s", home, hmagic); 227 228 /* First, try to get a magic file from user-application data */ 229 if ((home = getenv("LOCALAPPDATA")) != NULL) 230 _w32_append_path(&hmagicpath, "%s%s", home, hmagic); 231 232 /* Second, try to get a magic file from the user profile data */ 233 if ((home = getenv("USERPROFILE")) != NULL) 234 _w32_append_path(&hmagicpath, 235 "%s/Local Settings/Application Data%s", home, hmagic); 236 237 /* Third, try to get a magic file from Common Files */ 238 if ((home = getenv("COMMONPROGRAMFILES")) != NULL) 239 _w32_append_path(&hmagicpath, "%s%s", home, hmagic); 240 241 /* Fourth, try to get magic file relative to exe location */ 242 _w32_get_magic_relative_to(&hmagicpath, NULL); 243 244 /* Fifth, try to get magic file relative to dll location */ 245 _w32_get_magic_relative_to(&hmagicpath, _w32_dll_instance); 246 247 /* Avoid MAGIC constant - it likely points to a file within MSys tree */ 248 default_magic = hmagicpath; 249 return default_magic; 250 #endif 251 } 252 253 public const char * 254 magic_getpath(const char *magicfile, int action) 255 { 256 if (magicfile != NULL) 257 return magicfile; 258 259 magicfile = getenv("MAGIC"); 260 if (magicfile != NULL) 261 return magicfile; 262 263 return action == FILE_LOAD ? get_default_magic() : MAGIC; 264 } 265 266 public struct magic_set * 267 magic_open(int flags) 268 { 269 return file_ms_alloc(flags); 270 } 271 272 private int 273 unreadable_info(struct magic_set *ms, mode_t md, const char *file) 274 { 275 if (file) { 276 /* We cannot open it, but we were able to stat it. */ 277 if (access(file, W_OK) == 0) 278 if (file_printf(ms, "writable, ") == -1) 279 return -1; 280 #ifndef WIN32 281 if (access(file, X_OK) == 0) 282 if (file_printf(ms, "executable, ") == -1) 283 return -1; 284 #else 285 /* X_OK doesn't work well on MS-Windows */ 286 { 287 const char *p = strrchr(file, '.'); 288 if (p && (stricmp(p, ".exe") 289 || stricmp(p, ".dll") 290 || stricmp(p, ".bat") 291 || stricmp(p, ".cmd"))) 292 if (file_printf(ms, "writable, ") == -1) 293 return -1; 294 } 295 #endif 296 } 297 if (S_ISREG(md)) 298 if (file_printf(ms, "regular file, ") == -1) 299 return -1; 300 if (file_printf(ms, "no read permission") == -1) 301 return -1; 302 return 0; 303 } 304 305 public void 306 magic_close(struct magic_set *ms) 307 { 308 if (ms == NULL) 309 return; 310 file_ms_free(ms); 311 } 312 313 /* 314 * load a magic file 315 */ 316 public int 317 magic_load(struct magic_set *ms, const char *magicfile) 318 { 319 if (ms == NULL) 320 return -1; 321 return file_apprentice(ms, magicfile, FILE_LOAD); 322 } 323 324 #ifndef COMPILE_ONLY 325 /* 326 * Install a set of compiled magic buffers. 327 */ 328 public int 329 magic_load_buffers(struct magic_set *ms, void **bufs, size_t *sizes, 330 size_t nbufs) 331 { 332 if (ms == NULL) 333 return -1; 334 return buffer_apprentice(ms, RCAST(struct magic **, bufs), 335 sizes, nbufs); 336 } 337 #endif 338 339 public int 340 magic_compile(struct magic_set *ms, const char *magicfile) 341 { 342 if (ms == NULL) 343 return -1; 344 return file_apprentice(ms, magicfile, FILE_COMPILE); 345 } 346 347 public int 348 magic_check(struct magic_set *ms, const char *magicfile) 349 { 350 if (ms == NULL) 351 return -1; 352 return file_apprentice(ms, magicfile, FILE_CHECK); 353 } 354 355 public int 356 magic_list(struct magic_set *ms, const char *magicfile) 357 { 358 if (ms == NULL) 359 return -1; 360 return file_apprentice(ms, magicfile, FILE_LIST); 361 } 362 363 private void 364 close_and_restore(const struct magic_set *ms, const char *name, int fd, 365 const struct stat *sb) 366 { 367 if (fd == STDIN_FILENO || name == NULL) 368 return; 369 (void) close(fd); 370 371 if ((ms->flags & MAGIC_PRESERVE_ATIME) != 0) { 372 /* 373 * Try to restore access, modification times if read it. 374 * This is really *bad* because it will modify the status 375 * time of the file... And of course this will affect 376 * backup programs 377 */ 378 #ifdef HAVE_UTIMES 379 struct timeval utsbuf[2]; 380 (void)memset(utsbuf, 0, sizeof(utsbuf)); 381 utsbuf[0].tv_sec = sb->st_atime; 382 utsbuf[1].tv_sec = sb->st_mtime; 383 384 (void) utimes(name, utsbuf); /* don't care if loses */ 385 #elif defined(HAVE_UTIME_H) || defined(HAVE_SYS_UTIME_H) 386 struct utimbuf utbuf; 387 388 (void)memset(&utbuf, 0, sizeof(utbuf)); 389 utbuf.actime = sb->st_atime; 390 utbuf.modtime = sb->st_mtime; 391 (void) utime(name, &utbuf); /* don't care if loses */ 392 #endif 393 } 394 } 395 396 #ifndef COMPILE_ONLY 397 398 /* 399 * find type of descriptor 400 */ 401 public const char * 402 magic_descriptor(struct magic_set *ms, int fd) 403 { 404 if (ms == NULL) 405 return NULL; 406 return file_or_fd(ms, NULL, fd); 407 } 408 409 /* 410 * find type of named file 411 */ 412 public const char * 413 magic_file(struct magic_set *ms, const char *inname) 414 { 415 if (ms == NULL) 416 return NULL; 417 return file_or_fd(ms, inname, STDIN_FILENO); 418 } 419 420 private const char * 421 file_or_fd(struct magic_set *ms, const char *inname, int fd) 422 { 423 int rv = -1; 424 unsigned char *buf; 425 struct stat sb; 426 ssize_t nbytes = 0; /* number of bytes read from a datafile */ 427 int ispipe = 0; 428 int okstat = 0; 429 off_t pos = CAST(off_t, -1); 430 431 if (file_reset(ms, 1) == -1) 432 goto out; 433 434 /* 435 * one extra for terminating '\0', and 436 * some overlapping space for matches near EOF 437 */ 438 #define SLOP (1 + sizeof(union VALUETYPE)) 439 if ((buf = CAST(unsigned char *, malloc(ms->bytes_max + SLOP))) == NULL) 440 return NULL; 441 442 switch (file_fsmagic(ms, inname, &sb)) { 443 case -1: /* error */ 444 goto done; 445 case 0: /* nothing found */ 446 break; 447 default: /* matched it and printed type */ 448 rv = 0; 449 goto done; 450 } 451 452 #ifdef WIN32 453 /* Place stdin in binary mode, so EOF (Ctrl+Z) doesn't stop early. */ 454 if (fd == STDIN_FILENO) 455 _setmode(STDIN_FILENO, O_BINARY); 456 #endif 457 if (inname != NULL) { 458 int flags = O_RDONLY|O_BINARY|O_NONBLOCK|O_CLOEXEC; 459 errno = 0; 460 if ((fd = open(inname, flags)) < 0) { 461 okstat = stat(inname, &sb) == 0; 462 #ifdef WIN32 463 /* 464 * Can't stat, can't open. It may have been opened in 465 * fsmagic, so if the user doesn't have read permission, 466 * allow it to say so; otherwise an error was probably 467 * displayed in fsmagic. 468 */ 469 if (!okstat && errno == EACCES) { 470 sb.st_mode = S_IFBLK; 471 okstat = 1; 472 } 473 #endif 474 if (okstat && 475 unreadable_info(ms, sb.st_mode, inname) == -1) 476 goto done; 477 rv = 0; 478 goto done; 479 } 480 #if O_CLOEXEC == 0 && defined(F_SETFD) 481 (void)fcntl(fd, F_SETFD, FD_CLOEXEC); 482 #endif 483 } 484 485 if (fd != -1) { 486 okstat = fstat(fd, &sb) == 0; 487 if (okstat && S_ISFIFO(sb.st_mode)) 488 ispipe = 1; 489 if (inname == NULL) 490 pos = lseek(fd, CAST(off_t, 0), SEEK_CUR); 491 } 492 493 /* 494 * try looking at the first ms->bytes_max bytes 495 */ 496 if (ispipe) { 497 if (fd != -1) { 498 ssize_t r = 0; 499 500 while ((r = sread(fd, RCAST(void *, &buf[nbytes]), 501 CAST(size_t, ms->bytes_max - nbytes), 1)) > 0) { 502 nbytes += r; 503 if (r < PIPE_BUF) break; 504 } 505 } 506 507 if (nbytes == 0 && inname) { 508 /* We can not read it, but we were able to stat it. */ 509 if (unreadable_info(ms, sb.st_mode, inname) == -1) 510 goto done; 511 rv = 0; 512 goto done; 513 } 514 515 } else if (fd != -1) { 516 /* Windows refuses to read from a big console buffer. */ 517 size_t howmany = 518 #ifdef WIN32 519 _isatty(fd) ? 8 * 1024 : 520 #endif 521 ms->bytes_max; 522 if ((nbytes = read(fd, RCAST(void *, buf), howmany)) == -1) { 523 if (inname == NULL && fd != STDIN_FILENO) 524 file_error(ms, errno, "cannot read fd %d", fd); 525 else 526 file_error(ms, errno, "cannot read `%s'", 527 inname == NULL ? "/dev/stdin" : inname); 528 goto done; 529 } 530 } 531 532 (void)memset(buf + nbytes, 0, SLOP); /* NUL terminate */ 533 if (file_buffer(ms, fd, okstat ? &sb : NULL, inname, buf, CAST(size_t, nbytes)) == -1) 534 goto done; 535 rv = 0; 536 done: 537 free(buf); 538 if (fd != -1) { 539 if (pos != CAST(off_t, -1)) 540 (void)lseek(fd, pos, SEEK_SET); 541 close_and_restore(ms, inname, fd, &sb); 542 } 543 out: 544 return rv == 0 ? file_getbuffer(ms) : NULL; 545 } 546 547 548 public const char * 549 magic_buffer(struct magic_set *ms, const void *buf, size_t nb) 550 { 551 if (ms == NULL) 552 return NULL; 553 if (file_reset(ms, 1) == -1) 554 return NULL; 555 /* 556 * The main work is done here! 557 * We have the file name and/or the data buffer to be identified. 558 */ 559 if (file_buffer(ms, -1, NULL, NULL, buf, nb) == -1) { 560 return NULL; 561 } 562 return file_getbuffer(ms); 563 } 564 #endif 565 566 public const char * 567 magic_error(struct magic_set *ms) 568 { 569 if (ms == NULL) 570 return "Magic database is not open"; 571 return (ms->event_flags & EVENT_HAD_ERR) ? ms->o.buf : NULL; 572 } 573 574 public int 575 magic_errno(struct magic_set *ms) 576 { 577 if (ms == NULL) 578 return EINVAL; 579 return (ms->event_flags & EVENT_HAD_ERR) ? ms->error : 0; 580 } 581 582 public int 583 magic_getflags(struct magic_set *ms) 584 { 585 if (ms == NULL) 586 return -1; 587 588 return ms->flags; 589 } 590 591 public int 592 magic_setflags(struct magic_set *ms, int flags) 593 { 594 if (ms == NULL) 595 return -1; 596 #if !defined(HAVE_UTIME) && !defined(HAVE_UTIMES) 597 if (flags & MAGIC_PRESERVE_ATIME) 598 return -1; 599 #endif 600 ms->flags = flags; 601 return 0; 602 } 603 604 public int 605 magic_version(void) 606 { 607 return MAGIC_VERSION; 608 } 609 610 public int 611 magic_setparam(struct magic_set *ms, int param, const void *val) 612 { 613 if (ms == NULL) 614 return -1; 615 switch (param) { 616 case MAGIC_PARAM_INDIR_MAX: 617 ms->indir_max = CAST(uint16_t, *CAST(const size_t *, val)); 618 return 0; 619 case MAGIC_PARAM_NAME_MAX: 620 ms->name_max = CAST(uint16_t, *CAST(const size_t *, val)); 621 return 0; 622 case MAGIC_PARAM_ELF_PHNUM_MAX: 623 ms->elf_phnum_max = CAST(uint16_t, *CAST(const size_t *, val)); 624 return 0; 625 case MAGIC_PARAM_ELF_SHNUM_MAX: 626 ms->elf_shnum_max = CAST(uint16_t, *CAST(const size_t *, val)); 627 return 0; 628 case MAGIC_PARAM_ELF_NOTES_MAX: 629 ms->elf_notes_max = CAST(uint16_t, *CAST(const size_t *, val)); 630 return 0; 631 case MAGIC_PARAM_REGEX_MAX: 632 ms->regex_max = CAST(uint16_t, *CAST(const size_t *, val)); 633 return 0; 634 case MAGIC_PARAM_BYTES_MAX: 635 ms->bytes_max = *CAST(const size_t *, val); 636 return 0; 637 case MAGIC_PARAM_ENCODING_MAX: 638 ms->encoding_max = *CAST(const size_t *, val); 639 return 0; 640 default: 641 errno = EINVAL; 642 return -1; 643 } 644 } 645 646 public int 647 magic_getparam(struct magic_set *ms, int param, void *val) 648 { 649 if (ms == NULL) 650 return -1; 651 switch (param) { 652 case MAGIC_PARAM_INDIR_MAX: 653 *CAST(size_t *, val) = ms->indir_max; 654 return 0; 655 case MAGIC_PARAM_NAME_MAX: 656 *CAST(size_t *, val) = ms->name_max; 657 return 0; 658 case MAGIC_PARAM_ELF_PHNUM_MAX: 659 *CAST(size_t *, val) = ms->elf_phnum_max; 660 return 0; 661 case MAGIC_PARAM_ELF_SHNUM_MAX: 662 *CAST(size_t *, val) = ms->elf_shnum_max; 663 return 0; 664 case MAGIC_PARAM_ELF_NOTES_MAX: 665 *CAST(size_t *, val) = ms->elf_notes_max; 666 return 0; 667 case MAGIC_PARAM_REGEX_MAX: 668 *CAST(size_t *, val) = ms->regex_max; 669 return 0; 670 case MAGIC_PARAM_BYTES_MAX: 671 *CAST(size_t *, val) = ms->bytes_max; 672 return 0; 673 case MAGIC_PARAM_ENCODING_MAX: 674 *CAST(size_t *, val) = ms->encoding_max; 675 return 0; 676 default: 677 errno = EINVAL; 678 return -1; 679 } 680 } 681